Light Bending Planets: Hubble Helps Find World With Two Suns


A light bending method led to the discovery of a planet orbiting two stars instead of one. Albert Einstein‘s work contributed to this development.

In a paper published in The Astronomical Journal, David Bennett revealed that for the very first time, using NASA/ESA Hubble Space Telescope, scientists have been able to spot a circumbinary planet – a planet circling two stars.

The giant gas planet with a mass similar to Saturn was observed during the Optical Gravitational Lensing Experiment or OGLE. Scientists always had a knowledge of the existence of many planets that revolve around two, three or more stars, but this is the first time they have been able to confirm it.

To accomplish such a feat, astronomers used the light bending technique known as gravitational microlensing. This is how the method works:

“A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer; that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein’s general theory of relativity.(Classical physics also predicts the bending of light, but only half that predicted by general relativity.”

The exoplanet, which has been given the name OGLE-2007-BLG-349, is about 8,000 light-years away from Earth and is located in the center of the Milky Way​.

According to the paper, it was originally discovered in 2007 by ground-based observations from telescopes around the world including New Zealand, Chile, and South Africa. Moreover, scientists believed that the planet was orbiting one star.

However, they later identified two red dwarf stars that are 11 million kilometers (7 million miles) apart. The newly discovered planet orbits 480 million kilometers (300 million miles) from the two stars.

Bennett, of NASA’s Goddard Space Flight Center​ in Greenbelt, Maryland and the paper’s first author, said in a statement:

“The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star.”

Bennett went on to reveal that the Hubble Space Telescope made it possible for them to have a better view of “the brightness expected of two closely orbiting red dwarf stars.” Andrzej Udalski, from the University of Warsaw, Poland, co-author of the study, added:

“OGLE has detected over 17,000 microlensing events, but this is the first time such an event has been caused by a circumbinary planetary system.”

The astronomers said that now they know the light bending technique can accurately detect events caused by circumbinary planets, they hope other experts in this field will use it to search for other exoplanets.

Yiannis Tsapras, a co-author of the study from the Astronomisches Rechen-Institut in Heidelberg, Germany, had the following to say:

“This discovery, suggests we need to rethink our observing strategy when it comes to stellar binary-lensing events. This is an exciting discovery for microlensing”.

This discovery has many wondering, what will the Hubble Space Telescope spot next?